The present invention relates to a roller bearing for linear sliding motion and a feed table for linear sliding motion making use of the roller bearing.
Nowadays, the bearings for guiding a linear motion, as well as feed tables find uses for various industrial purposes and fields including machining centers, numerical control lathes and other machine tools, and for sliding parts of various machines such as automatic tool exchangers, automatic welders, injection machines, industrial robots, and so forth.
Most of the known bearings and tables of the kind described employ balls as the means for guiding linear sliding motion of the slider along the track shaft. The slider, as well as the track shaft, is constructed to have a cross-section which is symmetrical with respect to the vertical plane containing the longitudinal central axis thereof, and both arm or sleeve portions of the slider embrace corresponding shoulder portions of the track shaft in order to prevent the slider from floating above the track shaft.
The sliding contact between the slider and the track shaft is made through trains of balls. In order to bear a heavy load, it is necessary to elongate the loaded regions of the endless tracks in the track shaft so that the load may be shared by a greater number of balls, resulting in an increased size of the slider. On the other hand, the track shaft is provided with pairs of ball-rolling grooves formed in the surfaces of respective shoulder portions. Loaded balls on the slider roll along these ball-rolling grooves so that the balls in each pair of ball-rolling grooves clamp the corresponding shoulder portion of the track shaft so as to bear loads acting in all directions. Thus, the known bearing or feed table of the type described requires four grooves formed in the track shaft and four endless tracks in the slider. Therefore, the production of such slider and track shaft requires a large number of steps, particularly for the cutting and finishing of these grooves and tracks, as well as an impractically large number of parts, resulting in an increased cost of production.